Apparatus for continuous casting processes



Oct. 15, 1940. s. JUNGHANS APPARATUS FOR CONTINUOUS CASTING PROCESSESFiled Jan. 13, 1958 3 Sheets-Sheet 1 Oct. 15, 1940. JUNGHANS 2,218,171

APPARATUS FOR CONTINUOUS CASTING PROCESSES Filed Jan. 13, 1938 3Sheets-Sheet 2 Oct. 15, 1940. s. JUNGHANS APPARATUS FOR CONTINUOUSCASTING PROCESSES Filed Jan. 13, 1938 '3 Sheets-Sheet 5 Patented Oct.15,

UNITED STATES APPARATUS FOR CONTINUOUS CASTING PROCESSES SiegfriedJunghans, Stuttgart, Germany Application January 13, 1938, Serial No.

In Germany September 15, 1936 1 Claim.

The invention relates to metal casting, and pertains particularly todevices by means of which the molten metal (high and low melting pointmetals and metal alloys) is conveyed during the casting (and especiallyin continuous casting) to the casting moulds as uniformly as possible asregards quantity and speed.

In the various continuous casting processes one of the principalconditions for producing a satisfactory casting is that a constantlyuniform rate ofdischarge must be maintained.

The present invention proposes basically three different fundamentalsolutions of the problem of the uniform feeding of the metal, as beingthe most suitable for the various working conditions (casting of largequantities in steel and copper foundries etc. or casting in small ormedium foundries etc.).

In all the known continuous casting processes which have hitherto beenapplied in practice, a uniform rate of discharge of the metal entailscertain limitations as regards the casting speed (which is in most casesslower than in the normal processes hitherto applied) and also owing tothe necessity of having available the requisite durable materials forthe pipe lines, conduits and channels for conveying continuously theliquid metal. Owing to these limitations it has not been possiblehitherto to utilise the continuous process for the casting of largequantities, such as occur in steel works, copper and other foundries.One of the plants proposed in the present invention makes use of adistributing container into which the liquid metal is conveyed from oneor more melting or holding furnaces by means of one or more ladles. Thedistributing container consists preferably of a main chamber and severalside chambers which branch from the main chamber and can be shut oiffrom the main chamber.. From each of these side chambers a nozzle leadsto a corresponding mold. The nozzles are adapted to be replaced byothers of the same. or of a different cross-sectional area of discharge.The number of molds working can be regulatedby shutting oif or openingthe requisite number of side chambers, the total cross-sectional area ofthe nozzles working being such as to be able to deal with the maximumdischarge from the ladle or from the furnace into the distributingcontainer. Fluctuations in the discharge from the ladle or from thefurnace, due to diminution of the amount or the height of the metal, aremet with by regulating, i. e. increasing accordingly a pneumaticpressure in the ladle or in the furnace in order to attain a constantlyuniform discharge from the ladle into the container. The plant iscapable of being adapted in every way to the working conditions andrequirements prevailing at any time. v

A second plant for maintaining a uniform rate of discharge of themolten-metal into the molds is operated according to the followingconditions. In certain continuous processes a uniform rate of dischargeis obtained, for example, by conveying the metal to the mold through arising-pipe in which exists a correctly proportioned .pressure, or againby conveying the metal via a container from which it is discharged at auniform rate under pressure due to the height of fall.

In the case of high-melting point metals and metal alloys, such assteel, copper, tungsten, and the like, or in the case of metalsaffecting the pipe lines, conduits and channels to a high extent,difficulties arise owing to the fact that the refractory substance ofwhich the nozzles are made are 29 unable to withstand the hightemperatures without undergoing an alteration of their physicalcharacteristics so that the cross-sectional areas of the nozzles changeand thus influence the uniformity of the rate of discharge of the metal.is true that this drawback can be eliminated both as regards enlargementand narrowing of the nozzles, by altering the pressure during thecasting process by means of a pressure line, but as this requires apressure plant which is complicated and is still further complicatedowing to the fact that the pressure must be accurately proportioned tothe constantly varying cross-sectional nozzle areas. In castingprocesses in which Itgg per se very 30 the molten metal is conveyed viaa container, from 5 which the molten metal is discharged by gravity,there is however no possibility of eflecting'such regulation.

Now, as no substances are known to date which will withstand these hightemperatures or the attacks of certain metals without physical changes,

another method must be found for obtaining a uniform rate of dischargeof these high melting point metals in continuous casting processes.

According to the invention this new method consists in that, in the caseof the above mentioned plant, the metal is conveyedvia a container whichis provided with several nozzles, which can be connected anddisconnected separately and also be replaced. In this case however onlyone 50 nozzle is worked at a time. After some time, when the sectionalarea of this nozzle has altered to such an extent as to interfere withthe uniformity of the rate of discharge, this nozzle is disconnected andanother nozzle put into action.

. of whether the molten mass The worn nozzle can then be renewed so thatwhen the second nozzle in turn is worn out, the first nozzle can be putinto action again in place of the second nozzle.

This means of maintaining a uniform rate of discharge is applicable toall cases, irrespective is discharged under its own, or under auxiliarypressure, since also in the latter case no special regulating devicesneed be provided for the auxiliary pressure.

The third solution relating to a plant for maintaining a uniform rate ofdischarge to the mold is intended for the following conditions. Asmentioned above, the molten mass is conveyed to the nozzle from thefurnace or from some other container, by means of a path which includesa fall the height of which can be regulated, or by means for producingpressure in some other way for the purpose of maintaining a uniform rateof discharge in continuous casting processes. Now, the aim of theinvention is in the first place to eliminate the drawback which arisesin such a plant owing to the fact that the molten mass is conveyed underpressure, and in the second place to offer the possibility of constantlymaintaining a uniform rate of discharge in such plants where for somereason or other the pressure is not specially regulated.

The main characteristic of the third plant therefore consists in that anintermediate container is provided between the container which holds themolten mass, that is the melting furnace or a separate heating furnace,and the nozzle from which the molten mass is discharged at a uniformrate into the mold, the head of the molten mass being kept at a constantlevel in this intermediate container. For this purpose the dischargefrom the main container into the intermediate container is kept somewhatlarger than the discharge from the latter through the nozzle and theexcess metal thus accruing is removed from the intermediate containervia an overflow drain.

The fundamental idea of the invention resides therefore in therecognition of the fact that where the quantity poured in equals thequantity discharged it is impossible to maintain a uniform rate ofdischarge throughout or a uniform rate of discharge can at least bemaintained only with difliculty. Secondly, the invention takes intoconsideration the fact that so long as the discharge continues the levelof the metal in the main container must: continue to fall, thereby alsodecreasing the pressure and thus altering the rate of discharge withincertain limits, so that even if the discharge from the main containerwere equal to the discharge through the nozzles, the changing level ofthe liquid in the main container would still bring about a changing rateof feed to the nozzles. For this reason provision is made for the feedto the nozzle and to the (intermediate container from which the nozzlebranches ofi, to be always greater than the discharge from the nozzleand for the excess metal to be drained away.

In this way it is possible to obtain automatically with simple means acorrect regulating of the discharge of metal from the nozzle into themould.

The excess which is discharged through the overflow drain is preferablycollected in a separate accumulator so that it can be used again later.

The accompanying drawings illustrate by way of example three differentplants constructed according to the invention.

Figures 1 and 2 illustrate the first plant, which is provided, forexample, for casting purposes in a steel foundry, these figures beingrespectively a side view, partly in section, and a plan view.

Figure 3 shows a section on the line III-III of Figure 2.

Figures 4' to 8 illustrate the second plant, the essentialcharacteristics of which are mentioned above.

Figure 4 is a plan view of a long container.

Figure 5 is a front view, partly in section, of a casting plant having acontainer according to Figure 4.

Figure 6 is a sectional view of Figure 4.

Figure 7 is a plan view of a circular and radially arranged container,and

Figure 8 is a sectional view of Figure 7.

Figures 9 and 10 illustrate in longitudinal section two embodiments ofthe third plant.

In the first casting plant shown in Figures 1 to 3, I is a rectangularcontainer made of refractory bricks and having two bosses, 2 and 3, uponwhich the casting ladles containing the liquid metal can be placed.

4 are the narrow side chambers which branch off from the main containerl, and lead to the nozzles 5.

6 are slides made of refractory bricks, by means of which it is possibleto admit or shut off the flow of metal from the main container l to theside chambers 4, each slide being separately controlled by means of thehandles 1.

Each nozzle 5 has an outlet into one of the known devices used incontinuous casting processes or into a mold, which are not here shownindetail as they do not form part of the invention. The ladles A whichcontain from. 5 to 20 tons of molten metal according to the size of themelting furnace (one complete charge) have the usual plug stoppers B andcan be hermetically sealed by means of a cover C.

The sectional areas of the nozzles 5 depend upon the sectional area .ofthe casting to be cast and it may therefore be advantageous to adapt thenozzles to be detachable or in some other way replaceable. The totalsectional area of the nozzles 5 must however always equal the maximumdischarge from the ladle, in other words, the total sectional area ofthe nozzles in use at any time must be'so proportioned as to allow themto deal with the maximum discharge from the ladle, that is to say thequantity which discharges when the ladle is quite full. As of dischargefrom the ladle diminishes as the quantity and thus also the height ofthe head of metal decreases, the requisite amount of pneumatic pressureis applied through pipe D during the discharge to the contents of theladle and to the contents of the container I which can be covered bymeans of the lid 9, for maintaining a' constant rate of discharge, untilthe ladle is empty and the ladle 3, being a full ladle, can reestablishthe desired rate of discharge.

- The regulation of the rate of discharge by -means of pressure need notbe resorted to, of course, until the usual regulation by means of theladle plug is no longer sufficient to ensure a uniform flow. Thishappens mainly when the outlet opening has been much enlarged by theliquid jet, or as often occurs owing to the varying nature of therefractory material the funnel walls have .expanded that is to say thehole has narrowed. In order to guard against the rate surprises in thisrespect and to be sure that by applying pressure a regulation of therate of discharge will result, endeavours should be made always to usesuch refractory material for the ladle as tends to expand rather than towear away. If material is used which wears away the plug opening must beso chosen initially on the basis of practical experience, that thewidening of the discharge opening progresses approximately at the samerate as the speed of the discharge tends to decrease owing to thedecreasing level of the molten mass, so that also at this point anequilibrium can be established.

As the sectional areas of the castings vary from time to time accordingto the manufacturing programme the container I is provided with therequisite number of side chambers 4 for obtaining a totalcross-sectional area of the nozzles, which in the-case of minimumcross-sectional area of the castings, will be able to deal with themaximum discharge from the ladle. When later on castings of largersectional area are to be cast, a corresponding number of side chambers 4and nozzles 5 are put out of action, by shutting off the respective sidechambers by means of the slides 6.

The container I and the side chambers 4 are so designed, that beforeputting the plant into service or, if necessary, also during castingoperations, they can be heated, and after starting up they can becovered, so that the molten metal, if necessary can be protected againstcoming into contact with oxygen. If necessary, for example in thecase ofcopper, the container I and the side chambers 4 can also be protected bymeans of a neutral gas which is admitted therein through suitabledevices.

In order to prevent technical errors from causing an overflow in thecontainer I or in the side chambers 4, the container I is provided at 8with an overflow drain, which drains oil any excess metal into acollecting device.

The plant described above, besides being highly adaptable at all timesto the prevailing working conditions; possesses the further advantagethat owing to the relatively large surface created by the container Iand the side chambers 4 in relation to the depth of the melt, smallerrors in the regulating of the discharge have only a very slight eifectupon the individual nozzles, so that also in this respect is meets thereqirements of heavy duty working in large steel works and foundries,while at the same time ensuring a relatively great measure of accuracy.

In the second plant shown in Figures 4 to 5, the rectangular container Iis provided with six side chambers II, which can be shut off from themain part III of the container by means of the slides I2. In the bottomsof the chambers II the nozzles I3 are inserted in such a way that theycan be cut on from the chambers II by means of the valves I4. The valvesI4 can be actuated from the outside by the rods I5 and I6. The slides I2can be adjusted also from the outside by means of the handles I'I.

The container I0 is, as may be clearly seen particularly in Figure 5,arranged upon a trolley I8, having two supports I9, the lower part ofwhich serves as a cylinder into which the upper part fits in the mannerof a ram. The container I0 can thus for example be raised or lowered asrequired by hydraulic means.

The method of working is as follows:

The container I0 is filled with molten metal, care being taken in knownmanner, for example until the nozzle No. l is above the mold 20. By

lowering the container I0 the nozzle No. 1 is lowered into the mold. Theslide I2 appertaining to the chamber No. 1 and the corresponding valveI4 can now be opened by means of the rods I1, and l5,- l6 so that themolten mass can flow from the container I0 into the mold 20. After sometime, when the nozzle No. 1 is no longer working properly, the valve I4and the slide I2 of chamber No. 1 are closed, the container I0 is raisedby means of the extensible support until the lower edge of the nozzle isagain above the upper edge of the mold 20, and the trolley is movedalong until the nozzle N0. 2 arrives at the mold 20. By lowering thecontainer ID the nozzle No. 2 is then lowered into the mold 20 so thatwhen the slide I2 and valve I4 appertaining thereto are opened thenozzle can be put into service by allowing the molten mass to bedischarged at a uniform rate into the mold 20. When this nozzle in turnwears, the same procedure is repeated, nozzles Nos. 3, 4, 5 etc. beingsuccessively brought into section. The worn nozzles can now be renewedso that when the last nozzle is worn, nozzle No. 1 can again be put intoservice.

The same working method applies to the circular or radially disposedembodiments illustrated in Figures 7 and 8.

The container III is in this embodiment adapted to be raised and loweredupon a single support I9,

and is in addition rotatable and provided along its periphery with theindividual chambers II, which are numbered 1 to 8. Each of thesechambers II can be disconnected by means of a slide I2 and the nozzlewhich is adapted to be detachable from the bottom of the chamber can bedisconnected by means of a valve I4.

Each of the chambers II to turn allows the molten mass to be dischargedthrough the nozzle I3 appertaining thereto into the mold 20, when thecorresponding slide I2 and valve I4 are open, and when this nozzle isworn the next chamber II and its nozzle are connected in the mannerdescribed above, whilst the worn nozzle is renewed.

In the plant illustrated to Figures 9 and 10,,

the embodiment shown in Figure 9 provides for an intermediate container22 adjacent to the furnace 2I, which is the melting furnace proper or aseparate heating furnace, the nozzle 23 conveying the metal from thiscontainer to the mold 20. The sectional area b of the outlet 24 in thebottom of the furnace 2I is so dimensioned that the discharge of moltenmass from this outlet into the intermediate container is always greaterthan the discharge from the nozzle 23, the sectional area a of which iscorrespondingly proportioned. The rate of discharge in addition to beingdetermined by the sectional area a of the nozzle is also determined bythe level h" in the intermediate container 22 and consequently there isarranged in the intermediate container an overflow drain 23 at a levelcorresponding to the level h", through which the excess metal can drainoff into the collecting container 26. The

result is that quite independently or the level or the liquid in thecontainer 2| the level of the liquid in the container 22 andconsequently also the rate of discharge from the nozzle 23 are keptconstant.

As however the changing level of the liquid in the container 2|generates a varying pressure, so that the rate of discharge through theopening 24 will vary, the sectional area b of the discharge outlet 24must be so proportioned that when the liquid in the container 2| hasreached the level h, the discharge into the intermediate container 22will still remain greater than the discharge from the nozzle 23. This,of course, causes a relatively large overflow at the beginning ofcasting when the level is higher.

In order to eliminate this excessively large overflow the embodimentshown in Figure 10 is provided with a float 21 in the intermediatecontainer by the aid of which the feed from the furnace 2| to theintermediate container 22 can be regulated.

In the embodiment according to Figure 10 the main container is as in thecase of the embodiment in Figure 9 also rigidly disposed, and the float21 in this instance regulates a plug 29, which is provided in theoverflow drain aperture 24 between the main container 2| and theintermediate container 22.

As may be clearly seen in Figures 9 and 10,

this arrangement aflords the possibility of arranging tor the wholeplant to work in airtight conditions, so that the molten mass cannot beattacked by the atmospheric oxygen. In the same way it is possible toheat the whole plant, that is to say the main container 2|, theintermediate container 22 and the nozzle 23, and, if desired, also theaccumulating container 26, so as to maintain the molten mass at therequisite casting temperature at all points.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:

Apparatus for continuously feeding molten metal into a plurality ofmolds for the production of continuous ingots, comprising a wide, openmain channel, a plurality of short secondary channels directly connectedto the said main channel, a nozzle connected with each of the saidsecondary channels, a plurality of molds into each of which one of thesaid nozzles extends, a ladle having an opening in its bottom adapted todischarge molten'metal into said main channel, and means to applyingpneumatic pressure to the molten metal in said ladle in order to controlthe rate of discharge therefrom.

SIEGFBIED J UNGHANS.

